This invention relates generally to the control and prevention of soilborne diseases and to the enhancement of plant health through the use of biological agents. More specifically, an effective and stable dry biomass delivery system for these agents is disclosed. Biocontrol formulations of this invention contain sporulated microbial biomass which, when moistened and added to soil or soilless mix, allows growth of the biocontrol agent through the soil or soilless mix to reduce infestation of soilborne plant pathogens and the diseases these pathogens cause to growing plants.
The use of biological agents for control of plant diseases is not itself a new idea, nor is the controlled release of such agents from a matrix. For example, Lewis et al., "Formulation and Delivery Systems for Biocontrol Agents Effective Against Soilborne Plant Pathogenic Fungi," Proceed. Intern. Symp. Control. Rel. Bioact. Mater., Vol. 12, pp. 341-3 (1985), describes the use of alginate pellets containing propagules of potential fungal and bacterial biocontrol isolates to reduce the incidence of damping-off diseases in cotton, sugar beets and radish seedlings. Similarly, Fravel et al., "Encapsulation of Potential Biocontrol Agents in an Alginate-Clay Matrix," Phytopathology, Vol. 75, pp. 772-7 (1985), discloses a method for the encapsulation in alginate pellets of microorganisms that have potential to control plant diseases.
Backman et al., "A System for the Growth and Delivery of Biological Control Agents to the Soil," Phytopathology, Vol. 65, pp. 819-21 (1975) describes a diatomaceous earth granule impregnated with molasses, disclosed as suitable for growth and delivery of Trichoderma harzianum. Paulitz et al., "Effect of Peat:Vermiculite Mixes Containing Trichoderma harzianum on Increased Growth Response of Radish," J. Amer. Soc. Hort. Sci., Vol. 111, pp. 810-16 (1986) describes addition of T. harzianum to mixes of Canadian sphagnum peat and vermiculite for increased growth of radishes, independent of detectable plant pathogens. European Patent Application No. 86309438.9 (Agracetus), discloses a fungal culture product in which a medium of ground vermiculite, a nutrient and water is prepared and inoculated with a microbial culture.
For purposes of this discussion, the term "mycofungicides" shall mean microbes which act in the control of fungal diseases in plants. Soilborne diseases, caused by about fifty genera of fungi, and a few bacteria and viruses, cause about 50% of the losses due to plant diseases. It is conservatively estimated that, in the United States alone, soilborne diseases cause at least $5 billion losses on crops annually. A major obstacle to the implementation of biological control is a lack of technology in developing and formulating effective and stable preparations which can be produced commercially and which will be accepted in agricultural and horticultural systems.